I shall start with a new bowline "on the block" until, of course proven otherwise, that belongs to the janus school of thought (see Ampersand), whose basic principle of returning structure's operation goes like this......
1. First construct the bowline collar.
2. Then clone it by capturing the out-going leg.
3. Last secure the tail with some maneuver, e.g. through nipping loop.
https://forum.igkt.net/index.php?topic=4877.0 The knot, obviously, is very close to the ampersand design, the best available bowline in my view, at least in its first four construction stages.
From the detail view of a bowline knot, the first two common stages are apparently the conventional collar formation, next is the out going eye leg capture, and last, tail threading under SP.
They just differ in the last two stages, whereon the ampersand secures the tail by threrading it over itself and down through the nipping loop, in between the collar structure legs, while this one, funnels the tug end under itself and back through the collar, retaining the tibness and an unknotted returning line of shaped 8 .
As shown, besides the lack of third rope diameter inside the nipping loop, the amount of friction, is sufficient enough for me to declare it as inherently secure.
It's also quite possible that it follows ampersand's response at heavy loading due to structure similarities.
What's in store, is a TIB tying method, starting from low level, basic TIB objects, with gradual progression to more sophisticated TIB structures.